I want to add  Plotly chart renderers to the rpivotTable() function from the
R package rpivotTable. I followed the instructions given in the Javascript Pivot Table Wiki to add optional extra renderers. Unfortunatey, following these instructions will lead to the default behaviour. Maybe I assigned the Java code to the wrong arguments. 
Here is a small example:
library(rpivotTable)
library(shiny)
server <- function(input, output){
  output$mypivot = renderRpivotTable({
    rpivotTable(
      Titanic,
      renderers = htmlwidgets::JS("$.extend($.pivotUtilities.renderers,
            $.pivotUtilities.plotly_renderers)"),
      rendererName = "Horizontal Stacked Bar Chart"
    )
  })
}
ui <- shinyUI(fluidPage(
  tags$head(tags$script(src = "https://cdn.plot.ly/plotly-latest.min.js")),
  rpivotTableOutput("mypivot"))
)
shinyApp(ui = ui, server = server) 
